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9.
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Topics/Subscriptions
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(no translation yet)
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Located in
mqtt.7.xml:48(title)
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10.
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Messages in mqtt are published on topics. There is no need to configure a topic, publishing on it is enough. Topics are treated as a hierarchy, using a slash (/) as a separator. This allows sensible arrangement of common themes to be created, much in the same way as a filesystem. For example, multiple computers may all publish their hard drive temperature information on the following topic, with their own computer and hard drive name being replaced as appropriate:
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(no translation yet)
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Located in
mqtt.7.xml:49(para)
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11.
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sensors/COMPUTER_NAME/temperature/HARDDRIVE_NAME
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(no translation yet)
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Located in
mqtt.7.xml:57(listitem)
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12.
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Clients can receive messages by creating subscriptions. A subscription may be to an explicit topic, in which case only messages to that topic will be received, or it may include wildcards. Two wildcards are available, <option>+</option> or <option>#</option>.
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(no translation yet)
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Located in
mqtt.7.xml:59(para)
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13.
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<option>+</option> can be used as a wildcard for a single level of hierarchy. It could be used with the topic above to get information on all computers and hard drives as follows:
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(no translation yet)
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Located in
mqtt.7.xml:63(para)
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14.
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sensors/+/temperature/+
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(no translation yet)
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Located in
mqtt.7.xml:67(listitem)
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15.
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As another example, for a topic of "a/b/c/d", the following example subscriptions will match:
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(no translation yet)
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Located in
mqtt.7.xml:69(para)
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16.
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a/b/c/d
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(no translation yet)
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Located in
mqtt.7.xml:72(para) mqtt.7.xml:89(para)
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17.
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+/b/c/d
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(no translation yet)
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Located in
mqtt.7.xml:73(para)
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18.
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a/+/c/d
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(no translation yet)
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Located in
mqtt.7.xml:74(para)
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